Well paid engineers congregate in CA because that's where the companies that hire well paid engineers congregate, and they (mostly) want those well paid engineers to come to the office every couple of days. I don't know how you could get the causality so completely backwards on this.
Well paid engineers congregate in California because it's a nice place to live if you can afford it.
Therefore if you want to hire the best engineers, and want an in-office work culture, you need to go to California.